Where excess argon is a problem, accurate, reliable dates typically can be obtained using harlequin2, 2001.

Geochronology and Thermochronology by the 40Ar/39Ar Method.

Time since recrystallization is calculated by measuring the ratio of the amount of The quickly cooled lavas that make nearly ideal samples for K–Ar dating also preserve a record of the direction and intensity of the local magnetic field as the sample cooled past the Curie temperature of iron.

The geomagnetic polarity time scale was calibrated largely using K–Ar dating.

In 2013 the K–Ar method was used by the Mars Curiosity rover to date a rock on the Martian surface, the first time a rock has been dated from its mineral ingredients while situated on another planet.

Results in the potassium-argon dating program at Berkeley are reported.

The ratio of the amount of K which was present at the beginning of the elapsed time period.

The potassium is quantified by flame photometry or atomic absorption spectroscopy.

Due to the long half-life, the technique is most applicable for dating minerals and rocks more than 100,000 years old.

For shorter timescales, it is unlikely that enough argon-40 will have had time to accumulate in order to be accurately measurable.

The amount of Argon sublimation that occurs is a function of the purity of the sample, the composition of the mother material, and a number of other factors.

These factors introduce error limits on the upper and lower bounds of dating, so that final determination of age is reliant on the environmental factors during formation, melting, and exposure to decreased pressure and/or open-air.